<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>css书写位置</title>
    <style>
       
        /* 内联 */
        h1{
            color: red;
        }
    </style> 
    <!-- 外部另起一个.css -->
    <link rel="stylesheet" href="./index.css">
</head>
<body>
    <!--行内-->
    <h1 style="">xx</h1>
</body>
</html>